Which of the following is correct ?

Options

A. Spores are invariably haploid
B. Gametes are generally haploid
C. Both spores and gametes are invariably
D. Gametes are invariably haploid

Answer

To solve the question "Which of the following is correct?" regarding spores and gametes, we will analyze the statements provided in the options step by step.

### Step 1: Understand the Definitions
- **Haploid (N)**: A cell with a single set of chromosomes.
- **Diploid (2N)**: A cell with two sets of chromosomes.

### Step 2: Analyze the First Statement
- **Statement**: "Spores are invariably haploid."
- **Analysis**: This statement is incorrect. While many spores are haploid, especially in organisms like fungi and some plants, there are also diploid spores in certain organisms. Therefore, it is not accurate to say that spores are always haploid.

### Step 3: Analyze the Second Statement
- **Statement**: "Gametes are generally haploid."
- **Analysis**: This statement is correct. Gametes (sperm and egg cells) are indeed haploid. They are essential for sexual reproduction, where two gametes fuse during fertilization to form a diploid zygote. However, the term "generally" can be misleading because gametes are always haploid in the context of sexual reproduction.

### Step 4: Analyze the Third Statement
- **Statement**: "Both spores and gametes are invariably haploid."
- **Analysis**: This statement is incorrect. As discussed, while gametes are always haploid, spores can be either haploid or diploid depending on the organism and the type of reproduction.

### Step 5: Analyze the Fourth Statement
- **Statement**: "Gametes are invariably haploid."
- **Analysis**: This statement is correct. Gametes are always haploid, as they must fuse during fertilization to restore the diploid state in the zygote.

### Conclusion
From the analysis, the correct statement is:
- **D**: "Gametes are invariably haploid."