Ethernet is a widely used networking technology for local area networks (LANs). It is a wired communication standard that allows devices to connect and communicate with each other over a common network. In an Ethernet network, multiple hosts can send and receive data simultaneously. However, there are limitations on the number of hosts that can successfully send data at the same time.

Ethernet Collision Detection
One of the key features of Ethernet is its ability to detect and handle collisions. When two or more hosts attempt to transmit data simultaneously on the network, a collision occurs. In such cases, the data sent by each host gets corrupted and needs to be retransmitted. Ethernet uses a protocol called Carrier Sense Multiple Access with Collision Detection (CSMA/CD) to manage collisions.

Explanation of the Answer
The correct answer to the given question is option 'B' - 2 hosts. This means that in an Ethernet network, only two hosts can send data simultaneously without collisions. Let's understand why this is the case.

CSMA/CD Protocol
The CSMA/CD protocol used in Ethernet works as follows:

1. Carrier Sense: Before attempting to transmit data, a host checks if the network is idle. If it detects that the network is busy (another host is already transmitting), it waits for the network to become idle.

2. Multiple Access: When the network is idle, the host can begin transmitting data.

3. Collision Detection: While transmitting data, the host continuously monitors the network for collisions. It listens for any signals that indicate another host is transmitting at the same time.

4. Collision Handling: If a collision is detected, the host stops transmitting, waits for a random period of time, and then retries the transmission.

Limitations on Simultaneous Transmission
The limitation on the number of hosts that can successfully send data simultaneously is due to the collision detection mechanism. When more than two hosts attempt to transmit data at the same time, the chances of collisions increase significantly. As the number of hosts increases, the probability of collisions also increases, leading to a decrease in the overall network efficiency.

To avoid excessive collisions and ensure reliable data transmission, Ethernet networks typically employ strategies such as network segmentation, switches, and routers. These devices divide the network into smaller segments and provide dedicated communication channels for different hosts, allowing for better simultaneous data transmission.

Therefore, in an Ethernet network, the maximum number of hosts that can successfully send data simultaneously without collisions is limited to two.