Directions: Read the following sentence to determine if there is any grammatical or contextual error within it. If there is an error, it will be in one part of the sentence. Identify the part in which the error exists and mark it as your answer. Please consider the part in bold as grammatically correct. If there is no error, select E, i.e., 'No error' as your answer. Please ignore punctuation errors.

The scientists discovered that removing (A) / the gene responsible for haemoglobin production in (B) / cartilage tissue lead to chondrocyte cell death, (C) / highlighting the essential role of (D) / haemoglobin in their survival. / No error (E)