A deficiency in the secretion of hormones from the thyroid gland can lead to various health issues, but the most significant consequence is sluggishness and growth retardation. The thyroid gland produces hormones called thyroxine (T4) and triiodothyronine (T3), which play a crucial role in regulating metabolism and growth in the body.

Option 1: Sluggishness and growth retardation are common symptoms of hypothyroidism, a condition characterized by low thyroid hormone levels. When the body lacks sufficient thyroid hormones, metabolism slows down, leading to feelings of fatigue and sluggishness. Additionally, inadequate thyroid hormone levels can impair growth and development, resulting in growth retardation.

Option 2: High blood pressure is not directly associated with a deficiency in thyroid hormone secretion. However, untreated hypothyroidism can cause fluctuations in blood pressure, leading to an increased risk of developing hypertension.

Option 3: Delayed development of secondary sex characteristics is not specifically linked to a deficiency in thyroid hormone secretion. This symptom is more commonly observed in conditions affecting the production of sex hormones, such as certain disorders of the pituitary gland or adrenal glands.

Option 4: Defective carbohydrate metabolism is not a direct consequence of a deficiency in thyroid hormone secretion. However, hypothy