Carbohydrates which give two molecules of mono-saccharides are called disaccharides. These are:

Options

A. maltose
B. cellulose
C. maltase
D. lactose

Answer

To solve the question regarding carbohydrates that yield two molecules of monosaccharides upon hydrolysis, we will analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Disaccharides**:
- Disaccharides are carbohydrates that consist of two monosaccharide units linked together. Upon hydrolysis (the process of breaking down a compound by adding water), they yield two monosaccharide molecules.

2. **Analyzing the Options**:
- **Option A: Maltose**
- Maltose is a disaccharide composed of two glucose units. When hydrolyzed, it produces two molecules of glucose. Therefore, Maltose is a disaccharide.

- **Option B: Cellulose**
- Cellulose is a polysaccharide made up of many glucose units linked together. It does not yield two monosaccharides upon hydrolysis; instead, it yields multiple glucose units. Therefore, Cellulose is not a disaccharide.

- **Option C: Maltase**
- Maltase is not a carbohydrate; it is an enzyme that catalyzes the hydrolysis of maltose into glucose. Thus, it does not fit the definition of a disaccharide.

- **Option D: Lactose**
- Lactose is a disaccharide composed of one glucose and one galactose unit. Upon hydrolysis, it yields one molecule of glucose and one molecule of galactose. Therefore, Lactose is also a disaccharide.

3. **Conclusion**:
- From the analysis, we find that both Maltose (Option A) and Lactose (Option D) are disaccharides as they yield two monosaccharide molecules upon hydrolysis.

### Final Answer:
The carbohydrates that give two molecules of monosaccharides are Maltose and Lactose.