1. Interpret the question

A tetrapeptide on complete hydrolysis gives:

• Gly
• Ala
• Val
• Leu

in equimolar proportion each.

This means the tetrapeptide contains one molecule each of these four different amino acids.

So the problem reduces to:

How many distinct sequences can be formed using 4 different amino acids, each used exactly once?

2. Count the number of possible sequences

For a peptide, changing the order of amino acids gives a different peptide because the N-terminal to C-terminal order matters.

Thus, the number of different tetrapeptides is the number of permutations of 4 distinct amino acids:

$4! = 4 \times 3 \times 2 \times 1 = 24$

3. Check options

• A: $32$ ❌
• B: $24$ ✅
• C: $8$ ❌
• D: $16$ ❌

4. Final answer

The number of tetrapeptides possible is:

$\boxed{24}$

So the correct option is B.