1. Interpret the data

   The protein contains $0.30\%$ glycine by mass.

   This means in $100\,\text{g}$ of protein, mass of glycine present is $0.30\,\text{g}$

2. Find moles of glycine in 100 g protein

   Molecular mass of glycine $= 75\,\text{g mol}^{-1}$

   So, moles of glycine in $100\,\text{g}$ protein: $n = \frac{0.30}{75} = 0.004\,\text{mol}$

3. Use the idea of minimum molar mass

   For the minimum molar mass of the protein, we assume each molecule of protein contains at least one glycine residue.

   Then, moles of protein in $100\,\text{g}$ sample must also be $0.004\,\text{mol}$.

4. Calculate molar mass of protein

   $M = \frac{100}{0.004} = 25000\,\text{g mol}^{-1}$

   $M = 25 \times 10^3\,\text{g mol}^{-1}$

5. Nearest integer asked for blank

   The blank is in $\underline{\hspace{2cm}} \times 10^3\,\text{g mol}^{-1}$

   Hence the required integer is $25$

Comparison with stored answer

Stored correct answer: $25$

My derived answer: $25$

They match.