下列变化属于物理变化的是（ ）
A：生铁炼钢
B：石油分馏
C：铁丝锈蚀
D：燃放焰火
组别
土壤含水量
光合速率（μmolCO2•m﹣2•s﹣1）
气孔导度（mmol•m﹣2•s﹣1）
细胞间CO2浓度（μmol•mol﹣1）
注：土壤能保持的水分最多时，土壤含水量为100%；气孔导度是气孔开放程度的指标，气孔导度越大，气孔开得越大．
A
75%
15.4
438.7
296.2
B
61%
13.8
349.3
271.5
C
47%
10.2
243.6
262.1
D
33%
4.4
115.9
308.2
This Sunday is grandpa's birthday. The Smith family are going to celebrate it at home, so they will have a busy weekend.
Saturday
Morning
Dad-clean the car in the garden
Mum-clean the kitchen and bedrooms of their house
Amy-have dance lessons in the gym
Rose--work on science projects in the library
Afternoon
Mum and Dad-buy some food at the supermarket
Amy and Rose-choose gifts and cards for grandpa
Evening
Watch TV together
Sunday
Mum---make a big birthday cake
Amy and Rose-wrap grandpa's gifts
Amy-help Mum cook delicious food
Rose-help Dad decorate the sitting room
Amy and Rose-give gifts to grandpa
The whole family-have a party
根据表格所提供信息，从每小题所给的A、B、C三个选项中，选出一个最佳答案。
