To solve this question, we need to change each consonant in the word "SEAL" to the next letter of the English alphabet while keeping the vowels unchanged.
The word "SEAL" has two consonants, 'S' and 'L'.
When we change 'S' to the next letter in the English alphabet, we get 'T'.
When we change 'L' to the next letter in the English alphabet, we get 'M'.
So, the word "SEAL" can be changed to "TEAM" by replacing 'S' with 'T' and 'L' with 'M'.
Therefore, the meaningful word formed by changing each consonant in the word "SEAL" is "TEAM".
Hence, the correct answer is option C) Three, as we can form one meaningful word "TEAM".