Solution:
When we toss a coin, there are two possible outcomes - Head (H) or Tail (T). As the coins are unbiased, the probability of getting either head or tail is 1/2 or 0.5.

To find the probability of getting 3 heads if 6 unbiased coins are tossed simultaneously, we need to use the formula for binomial probability distribution.

Binomial Probability Distribution:
The binomial probability distribution is a probability distribution that describes the number of successes in a fixed number of independent trials, where each trial has the same probability of success.

The formula for binomial probability distribution is given as:

P(X = k) = nCk * pk * (1-p)n-k

where,
P(X = k) is the probability of getting k successes
n is the total number of trials
k is the number of successes
p is the probability of success in each trial
(1-p) is the probability of failure in each trial
nCk is the binomial coefficient, given by nCk = n!/k!(n-k)!

Calculation:
Here, we need to find the probability of getting 3 heads, so k = 3.
n = 6, as 6 coins are tossed simultaneously.
p = 0.5, as the coins are unbiased.
(1-p) = 0.5, as the probability of failure is the same as the probability of success.

Using the formula for binomial probability distribution, we get:

P(X = 3) = 6C3 * (0.5)3 * (0.5)6-3
P(X = 3) = 20 * 0.125 * 0.125
P(X = 3) = 0.3125

Therefore, the probability of getting 3 heads if 6 unbiased coins are tossed simultaneously is 0.3125 or 31.25%. Hence, option (c) is the correct answer.

Total no. of events =2^6=64
probability of getting 3 heads=6C3 ways
6!/(6-3)!3! =20
probability =20/64. = 0.3125