**Statement Analysis:**

a) Reciprocating pumps are less efficient than centrifugal pumps.
b) Delivery from a reciprocating pump is pulsating.
c) Reciprocating pumps are suitable for large discharges and smaller heads.
d) For a negative slip to occur, a reciprocating pump must have a coefficient of discharge less than unity.

The correct statement is option 'B', which states that delivery from a reciprocating pump is pulsating.

**Explanation:**

Reciprocating pumps and centrifugal pumps are two different types of pumps used for fluid transportation. Let's analyze each statement to understand why option 'B' is correct.

a) Reciprocating pumps are less efficient than centrifugal pumps:
- This statement is incorrect. Efficiency is a measure of how well a pump converts input power into useful work. Both reciprocating and centrifugal pumps can have high efficiency depending on their design and operating conditions. It is not accurate to say that reciprocating pumps are always less efficient than centrifugal pumps.

b) Delivery from a reciprocating pump is pulsating:
- This statement is correct. Reciprocating pumps operate by using a piston or plunger to create a reciprocating motion that displaces the fluid. This reciprocating motion results in a pulsating flow, where the fluid is delivered in discrete pulses rather than a continuous stream. This pulsating flow can cause pressure fluctuations in the system.

c) Reciprocating pumps are suitable for large discharges and smaller heads:
- This statement is not entirely accurate. Reciprocating pumps are generally suitable for high-pressure applications where the head (pressure) requirement is relatively high. They are capable of generating high pressures but may have limitations in terms of discharge capacity. Centrifugal pumps, on the other hand, are better suited for high-flow, low-pressure applications.

d) For a negative slip to occur, a reciprocating pump must have a coefficient of discharge less than unity:
- This statement is incorrect. Slip refers to the difference between the theoretical and actual flow rates of a pump. Negative slip occurs when the actual flow rate is higher than the theoretical flow rate. It does not depend on the coefficient of discharge. The coefficient of discharge is a measure of how well a pump can convert the potential energy of the fluid into kinetic energy. It is not directly related to slip.

In conclusion, the correct statement is option 'B' because reciprocating pumps do deliver a pulsating flow.